A strength and deformation model for prestressed lightweight concrete slabs under two-way shear
Ahmed Farouk Deifalla
Abstract
Prestressed concrete slabs (PCS) are one of the top choices in many applications, which is due to their significantly improved performance compared to conventional normal-weight concrete slabs (NCS). However, very limited models exist for the two-way shear behavior of PCS, in particular, lightweight ones (PLCS). In this study, a two-way shear mechanical behavior model is developed for PCS, that accounts for all effective parameters and capable of predicting both strength and deformation. An experimental database of PCS was compiled from the literature with emphasis on lightweight concrete. A mechanical model developed by the author for lightweight concrete slabs (LCS) was adapted and modified in order to include the effect of prestressing in terms of the following components: (1) the membrane compression stress; (2) the prestressing eccentricity; and (3) the prestressing vertical component. The extended model was used to predict the behavior of PLCS and prestressed normal-weight concrete slabs (PNCS), which was compared to that using selected design codes and models. The model predicted the rotation accurately and consistently compared to the experimentally measured rotation. The strength predicted using the proposed model was better than existing ones concerning experimentally measured strength, yet it was found to be reasonably safe. However, conclusions are limited to the experimental database.